Thin film deposition

ABSTRACT

A method of preparing a surface for deposition of a thin film thereon, wherein the surface including a plurality of protrusions extending therefrom and having shadowed regions, includes locally treating at least one of the protrusions.

The claimed invention was made by, on behalf of, and/or in connectionwith one or more of the following parties to a joint universitycorporation research agreement: Regents of the University of Michigan,Princeton University, The University of Southern California, and theUniversal Display Corporation. The agreement was in effect on and beforethe date the claimed invention was made, and the claimed invention wasmade as a result of activities undertaken within the scope of theagreement.

FIELD

In a number of embodiments, devices, systems and methods hereof relateto organic electronic devices that are protected from environmentalelements such as moisture and oxygen.

BACKGROUND

The following information is provided to assist the reader inunderstanding technologies disclosed below and the environment in whichsuch technologies may typically be used. The terms used herein are notintended to be limited to any particular narrow interpretation unlessclearly stated otherwise in this document. References set forth hereinmay facilitate understanding the technologies or the background thereof.The disclosure of all references cited herein are incorporated byreference.

Opto-electronic devices that make use of organic materials are becomingincreasingly desirable for a number of reasons. Many of the materialsused to make such devices are relatively inexpensive, so organicopto-electronic devices have the potential for cost advantages overinorganic devices. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on a flexible substrate.Examples of organic opto-electronic devices include organic lightemitting devices (OLEDs), organic phototransistors, organic photovoltaiccells, and organic photodetectors. For OLEDs, the organic materials mayhave performance advantages over conventional materials. For example,the wavelength at which an organic emissive layer emits light maygenerally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage isapplied across the device. OLEDs are becoming an increasinglyinteresting technology for use in applications such as flat paneldisplays, illumination, and backlighting. Several OLED materials andconfigurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full colordisplay. Industry standards for such a display call for pixels adaptedto emit particular colors, referred to as “saturated” colors. Inparticular, these standards call for saturated red, green, and bluepixels. Color may be measured using CIE coordinates, which are wellknown to the art.

One example of a green emissive molecule is tris(2-phenylpyridine)iridium, denoted Ir(ppy)₃, which has the following structure:

In this structure, we depict the dative bond from nitrogen to metal(here, Ir) as a straight line.

As used herein, the term “organic” includes polymeric materials as wellas small molecule organic materials that may be used to fabricateorganic opto-electronic devices. “Small molecule” refers to any organicmaterial that is not a polymer, and “small molecules” may actually bequite large. Small molecules may include repeat units in somecircumstances. For example, using a long chain alkyl group as asubstituent does not remove a molecule from the “small molecule” class.Small molecules may also be incorporated into polymers, for example as apendent group on a polymer backbone or as a part of the backbone. Smallmolecules may also serve as the core moiety of a dendrimer, whichconsists of a series of chemical shells built on the core moiety. Thecore moiety of a dendrimer may be a fluorescent or phosphorescent smallmolecule emitter. A dendrimer may be a “small molecule,” and it isbelieved that all dendrimers currently used in the field of OLEDs aresmall molecules.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. Where a first layer isdescribed as “disposed over” a second layer, the first layer is disposedfurther away from substrate. There may be other layers between the firstand second layer, unless it is specified that the first layer is “incontact with” the second layer. For example, a cathode may be describedas “disposed over” an anode, even though there are various organiclayers in between.

As used herein, “solution processible” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

More details on OLEDs, and the definitions described above, can be foundin U.S. Pat. No. 7,279,704, which is incorporated herein by reference inits entirety.

It is difficult for currently available thin film deposition orencapsulation technologies to cover large size particles on OLEDs andother systems. The general trend is that larger particles requirethicker films to provide coverage, which results in longer process timeand increased cost.

OLEDs and other electronic/microelectronic devices including water vaporsensitive cathodes and organic materials degrade upon storage. Thedegradation is evidenced by formation of dark spots, which may be causedby the ingress of water vapor and oxygen vertically through the bulk ofthe thin film encapsulation (TFE) or through surface protrusion defects(particles) embedded in the TFE, or by the ingress of water vapor andoxygen horizontally through the edge of the TFE. In most cases, thedominant degradation mechanism is ingression of water vapor and oxygenthrough surface protrusions or particles.

One of the most studied thin film encapsulation technologies is amultilayer approach described, for example, in U.S. Pat. No. 6,548,912.The multilayer barrier of that approach includes alternate layers ofinorganic and polymer films. A pair of inorganic and polymer layers iscalled a dyad. The multilayer approach works on the principle ofdelaying the permeant molecules from reaching the device by forming longand tortuous diffusion paths. The multilayer approach toprotrusion/particles encapsulation provides redundancy in the number ofdyads. When the particle size is large, the required number of dyads canbe very large as illustrated in FIG. 1.

A number of common thin film deposition techniques used, for example,with inorganic materials/films are known to be anisotropic, directionalor directionally limited. It is thus very difficult for depositedinorganic films to cover shadowed region under a protrusion. Withreference to FIG. 2, a protrusion 10 may be defined as an entity thathas or creates a shadowed region 20. Shadowed region 20 may be definedwith respect to a columnar source of light having substantially the sameorientation as a directional deposition technique. In FIG. 1, light fromsuch a columnar source of light is represented by arrows 30, radiatingfrom above (in the orientation of FIG. 2) and orthogonal to a surface 40upon which protrusion 10 is positioned. Shadowed region 20 correspondsto the volume under the perimeter of protrusion 10 and above surface 40.In FIG. 2, protrusion 10 is illustrated as a spherical particle, butprotrusions can be of generally any shape (whether regular orirregular).

Referring again to FIG. 1, under the technique of U.S. Pat. No.6,548,912, inorganic barrier layer 60 a, 60 b, 60 c, and 60 d arealternately deposited with polymer layer 70 a, 70 b 70 c and 70 d on asurface of a device/substrate 50 upon which a plurality of protrusiondefects 10 (for example, particles) are present. Polymer layers 70 a, 70b 70 c and 70 d fill the shadowed region 20. However, protrusion 10 isrelatively large, and four dyads are required to fill shadowed region 20in FIG. 2. A fifth inorganic layer 60 e (illustrated in broken lines)will be able to provide continuous coverage along the surface aroundprotrusion 10. Generally, the thin film layer stack must have at leasthalf of the thickness of protrusion 10 to provide a good surface profileto support a continuous coating. Materials may be deposited on top ofthe protrusions (not shown in the figures).

Other approaches have been proposed to deposit thin film as, forexample, encapsulation barriers for microelectronic devices. One exampleis atomic layer deposition (ALD). However, it is difficult to providegood coverage of protrusions with ALD. Also, when the protrusion canmove (for example, in the case of particles), ALD has problems holdingthe protrusions in place.

U.S. Patent Application Publication No. 2008/0102223 discloses anencapsulation technique using a single layer barrier. Because thematerial is deposited in a plasma-enhanced chemical vapor deposition(PECVD) chamber, it is possible to achieve a good conformal coating tocover a protrusion. However, film thickness may need to be increased toadequately cover larger protrusion.

Increasing film thickness translates into longer deposition time, morematerial usage, and eventually higher cost. Furthermore, there is noguaranty that large protrusions can be fully covered even using thickerfilms.

BRIEF SUMMARY

In summary, one aspect provides a method of preparing a surface fordeposition of a thin film thereon, wherein the surface including aplurality of protrusions extending therefrom and having shadowedregions. The method includes locally treating at least one of theprotrusions. The local treatment of one or more protrusions may, forexample, be used to reduce a thickness of the thin film required toencapsulate the surface (as compared to the thickness required toencapsulate the surface without local treatment of the at least one ofthe protrusions).

In a number of embodiments, the method may further include defining athreshold value for at least one measurable aspect of the protrusions todetermine protrusions for which local treatment is to be effected andlocally treating protrusions for which the measurable aspect exceeds thethreshold value. The at least one measurable aspect may, for example, bea dimension of the protrusions, a projected area of the protrusions, ora volume of the protrusions. The method may further include scanning thesurface to determine the location on the surface of protrusions forwhich the measurable aspect exceeds the threshold value. Desiredtopological features other than protrusions may, for example, bedetermined and excluded from analysis for local treatment. In a numberof embodiments, the threshold value is determined at least in part onthe basis of a total actual cycle time required to cover protrusionsthat do not exceed the threshold value in a thin film depositionprocess. A thin barrier layer may be applied prior to applying thematerial to the at least one protrusion to protect against damage.

The at least one protrusion may, for example, be a defect. The defectmay, for example, include a particle on the surface. A plurality of theprotrusions may be locally treated, resulting in treatment of less than10% of an area of the surface. In a number of embodiments, a pluralityof the protrusions may be locally treated, resulting in treatment ofless than 1% of an area of the surface.

Locally treating the at least one protrusion may, for example, result inreduction of a volume associated with a shadowed region of the at leastone protrusion. Locally treating may, for example, include removal ofthe at least one protrusion or reduction in size of the at least oneprotrusion.

In a number of embodiments, locally treating includes applying amaterial to the at least one protrusion to reduce the volume associatedwith the shadowed region of the at least one protrusion. The applicationof the material may, for example, result in a surface of the materialextending beyond the perimeter of the protrusion. In a number ofembodiments, application of the material results in a surface of thematerial having an average perimeter which increases in a downwarddirection.

In a number of embodiments, the material is flowable. The material may,for example, be a liquid. The material/liquid may, for example, includea precursor to a polymer, and the method may further includespolymerizing the precursor.

In a number of embodiments, the surface of the protrusion adjacent tothe shadowed region has affinity for the material (for example, aliquid). For example, the surface of the protrusion adjacent to theshadowed region may be hydrophobic and the liquid may be non-polar, orthe surface of the protrusion adjacent to the shadowed region may behydrophilic and the liquid may be polar. The method may, for example,further include effecting at least one treatment whereby the surface ofthe protrusion adjacent to the shadowed region is caused to haveaffinity for the liquid greater than an affinity of the remainder of thesurface of the protrusion for the liquid and greater than an affinity ofthe surface for the liquid. The material/liquid may, for example,include acrylate compounds or epoxy compounds.

The material may, for example, be applied by inkjet printing or dropcoating to protrusions for which a measurable aspect exceeds a thresholdvalue.

In a number of embodiments wherein the surface of the protrusionadjacent to the shadowed region is caused to have affinity for theliquid greater than an affinity of the remainder of the surface of theprotrusion for the liquid and greater than an affinity of the surfacefor the liquid, the method further includes applying the liquid to atleast a portion of the surface including a plurality of protrusions andremoving a bulk of the liquid in a manner such that some of the liquidremains only in the vicinity of the surface of the protrusions adjacentto the shadowed region. A thin barrier layer may, for example, beapplied to the surface prior to application of the liquid to protectagainst damage.

A barrier layer applied to protect against damage may, for example,include at least one of an inorganic material, an organic material, or ametallic material. An inorganic material may, for example, be an oxide,a nitride, or an oxynitride. An organic material may, for example, be anacrylate or a siloxane. The barrier layer may, for example, be depositedby chemical vapor deposition, sputtering, e-beam, atomic layerdeposition, evaporation, or spin coating.

The surface may, for example, be a surface of a microelectronic device,and the thin film may be deposited to encapsulate the microelectronicdevice. The microelectronic device may, for example, include anintegrated circuit, a charge coupled device, a light emitting diode, alight emitting polymer device, an organic light emitting device, a metalsensor pad, a micro-disk laser, an electrochromic device, a photochromicdevice, a display, an organic electronic device, amicroelectromechanical system, a thin film transistor, or a solar cell.In a number of embodiments, the microelectronic device includes anorganic device such as an organic light emitting diode.

In a number of embodiments, the microelectronic device is formed on atleast one flexible substrate. In a number of embodiments, wherein thesurface is flexible and the protrusion is a particle defect, applicationof a material as described above results in fixing of the position ofthe particle defect relative to the surface.

The thin films applied herein can include a plurality of layers. Thethin film may, for example, include a layer of a first material and atleast a second layer of a second material different from the firstmaterial. The thin film may, for example, include at least one of aninorganic material, an organic material, or a metallic material. Aninorganic material may, for example, be an oxide, a nitride, or anoxynitride. An organic material may, for example, be an acrylate or asiloxane. The thin film may, for example, include a plurality of layers.In a number of embodiments, the thin film includes a layer of a firstmaterial and at least a second layer of a second material different fromthe first material.

In another aspect, a method of encapsulating a device including aplurality of protrusions extending therefrom includes locally treatingat least one of the protrusions. As described above, local treatment ofone or more protrusions may, for example, be used to reduce a thicknessof a thin film required to encapsulate the device, and depositing thethin film to encapsulate the device after local treatment of the atleast one protrusion. The method may, for example, further includedefining a threshold value for at least one measurable aspect of theprotrusions to determine protrusions for which local treatment is to beeffected. As described above, the method may further include depositinga protective, thin barrier layer on the device prior to locally treatingthe at least one protrusion.

In another aspect, an encapsulated device includes a surface comprisinga plurality of protrusions extending therefrom, and a thin filmdeposited to encapsulate the device, wherein at least one of theprotrusions has undergone local treatment prior to deposition of thethin film. As described above, local treatment of one or moreprotrusions may, for example, be used to reduce a thickness of the thinfilm required to encapsulate the device. In a number of embodimentsprotrusions exceeding a threshold value for at least one measurableaspect of the protrusions have undergone local treatment to reduce thethickness of the thin film required to encapsulate the device.

In a further aspect, a microelectronic device includes a surfacecomprising a plurality of protrusions extending therefrom, and a thinfilm deposited to encapsulate the microelectronic device, wherein atleast one of the protrusions has undergone local treatment prior todeposition of the thin film. Local treatment of one or more protrusionsmay, for example, be used to reduce a thickness of the thin filmrequired to encapsulate the microelectronic device. In a number ofembodiments, protrusions exceeding a threshold value for at least onemeasurable aspect of the protrusions have undergone local treatment toreduce the thickness of the thin film required to encapsulate themicroelectronic device.

In still a further aspect, system for preparing a surface for depositionof a thin film thereon, wherein the surface includes a plurality ofprotrusions extending therefrom which have shadowed regions, includes atleast one detecting device to locate protrusion satisfying a thresholdvalue for at least one measurable aspect of the protrusions and at leastone device to locally treat at least one of the protrusions for whichthe measurable aspect exceeds the threshold value.

The foregoing is a summary and thus may contain simplifications,generalizations, and omissions of detail; consequently, those skilled inthe art will appreciate that the summary is illustrative only and is notintended to be in any way limiting.

For a better understanding of the embodiments, together with other andfurther features and advantages thereof, reference is made to thefollowing description, taken in conjunction with the accompanyingdrawings. The scope of the claimed invention will be pointed out in theappended claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates a known process for covering protrusions in a thinfilm deposition technique or approach.

FIG. 2 illustrates a protrusion having or defining a shadowed region.

FIG. 3 illustrates an embodiment of organic light emitting device.

FIG. 4 illustrates an embodiment of an inverted organic light emittingdevice that does not have a separate electron transport layer.

FIG. 5 illustrates a flow chart for an embodiment of a method hereof.

FIG. 6 illustrates actions or procedures (a) through (e) of anembodiment of method hereof for depositing a thin film on, for example,a microelectronic device.

FIG. 7A illustrates removal of a particle and elimination of anassociated shadowed region using a vacuum pick-up device or vacuum tip.

FIG. 7B illustrates reduction of the size of a particle and reduction ofan associated shadowed region using a laser beam above the particle.

FIG. 7C illustrates reduction of the size of a particle and reduction ofan associated shadowed region using a laser beam generally parallel to asurface of a microelectronic device.

FIG. 8 illustrates actions or procedures (a) through (e) of anotherembodiment of method hereof for depositing a thin film on, for example,a microelectronic device.

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed betweenand electrically connected to an anode and a cathode. When a current isapplied, the anode injects holes and the cathode injects electrons intothe organic layer(s). The injected holes and electrons each migratetoward the oppositely charged electrode. When an electron and holelocalize on the same molecule, an “exciton,” which is a localizedelectron-hole pair having an excited energy state, is formed. Light isemitted when the exciton relaxes via a photoemissive mechanism. In somecases, the exciton may be localized on an excimer or an exciplex.Non-radiative mechanisms, such as thermal relaxation, may also occur,but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from theirsinglet states (“fluorescence”) as disclosed, for example, in U.S. Pat.No. 4,769,292, which is incorporated by reference in its entirety.Fluorescent emission generally occurs in a time frame of less than 10nanoseconds.

More recently, OLEDs having emissive materials that emit light fromtriplet states (“phosphorescence”) have been demonstrated. Baldo et al.,“Highly Efficient Phosphorescent Emission from OrganicElectroluminescent Devices,” Nature, vol. 395, 151-154, 1998;(“Baldo-I”) and Baldo et al., “Very high-efficiency green organiclight-emitting devices based on electrophosphorescence,” Appl. Phys.Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), which are incorporatedby reference in their entireties. Phosphorescence is described in moredetail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporatedby reference.

FIG. 3 illustrates an embodiment organic light emitting device 100. Thefigures are not necessarily drawn to scale. Device 100 may include asubstrate 110, an anode 115, a hole injection layer 120, a holetransport layer 125, an electron blocking layer 130, an emissive layer135, a hole blocking layer 140, an electron transport layer 145, anelectron injection layer 150, a protective layer 155, a cathode 160, anda barrier layer 170. Cathode 160 is a compound cathode having a firstconductive layer 162 and a second conductive layer 164. Device 100 maybe fabricated by depositing the layers described, in order. Theproperties and functions of these various layers, as well as examplematerials, are described in more detail in U.S. Pat. No. 7,279,704 atcols. 6-10, which are incorporated by reference.

More examples for each of these layers are available. For example, aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. No. 5,844,363, which is incorporated by reference in itsentirety. An example of a p-doped hole transport layer is m-MTDATA dopedwith F.sub.4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. PatentApplication Publication No. 2003/0230980, which is incorporated byreference in its entirety. Examples of emissive and host materials aredisclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which isincorporated by reference in its entirety. An example of an n-dopedelectron transport layer is BPhen doped with Li at a molar ratio of 1:1,as disclosed in U.S. Patent Application Publication No. 2003/0230980,which is incorporated by reference in its entirety. U.S. Pat. Nos.5,703,436 and 5,707,745, which are incorporated by reference in theirentireties, disclose examples of cathodes including compound cathodeshaving a thin layer of metal such as Mg:Ag with an overlyingtransparent, electrically-conductive, sputter-deposited ITO layer. Thetheory and use of blocking layers is described in more detail in U.S.Pat. No. 6,097,147 and U.S. Patent Application Publication No.2003/0230980, which are incorporated by reference in their entireties.Examples of injection layers are provided in U.S. Patent ApplicationPublication No. 2004/0174116, which is incorporated by reference in itsentirety. A description of protective layers may be found in U.S. PatentApplication Publication No. 2004/0174116, which is incorporated byreference in its entirety.

FIG. 4 illustrates an embodiment of inverted OLED 200. The deviceincludes a substrate 210, a cathode 215, an emissive layer 220, a holetransport layer 225, and an anode 230. Device 200 may be fabricated bydepositing the layers described, in order. Because the most common OLEDconfiguration has a cathode disposed over the anode, and device 200 hascathode 215 disposed under anode 230, device 200 may be referred to asan “inverted” OLED. Materials similar to those described with respect todevice 100 may be used in the corresponding layers of device 200. FIG. 4provides one example of how some layers may be omitted from thestructure of device 100.

The simple layered structure illustrated in FIGS. 3 and 4 is provided byway of non-limiting example, and it is understood that embodimentshereof may be used in connection with a wide variety of otherstructures. The specific materials and structures described areexemplary in nature, and other materials and structures may be used.Functional OLEDs may be achieved by combining the various layersdescribed in different ways, or layers may be omitted entirely, based ondesign, performance, and cost factors. Other layers not specificallydescribed may also be included. Materials other than those specificallydescribed may be used. Although various layers may be described asincluding a single material, it is understood that combinations ofmaterials, such as a mixture of host and dopant, or more generally amixture, may be used. Also, the layers may have various sublayers. Thenames given to the various layers herein are not intended to be strictlylimiting. For example, in device 200, hole transport layer 225transports holes and injects holes into emissive layer 220, and may bedescribed as a hole transport layer or a hole injection layer. In oneembodiment, an OLED may be described as having an “organic layer”disposed between a cathode and an anode. This organic layer may comprisea single layer, or may further comprise multiple layers of differentorganic materials as described, for example, with respect to FIGS. 3 and4.

Structures and materials not specifically described may also be used,such as OLEDs comprised of polymeric materials (PLEDs) such as disclosedin U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated byreference in its entirety. By way of further example, OLEDs having asingle organic layer may be used. OLEDs may be stacked, for example asdescribed in U.S. Pat. No. 5,707,745 to Forrest et al, which isincorporated by reference in its entirety. The OLED structure maydeviate from the simple layered structure illustrated in FIGS. 3 and 4.For example, the substrate may include an angled reflective surface toimprove out-coupling, such as a mesa structure as described in U.S. Pat.No. 6,091,195 to Forrest et al., and/or a pit structure as described inU.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated byreference in their entireties.

Unless otherwise specified, any of the layers of the various embodimentsmay be deposited by any suitable method. For the organic layers,preferred methods include thermal evaporation, ink-jet, such asdescribed in U.S. Pat. Nos. 6,013,982 and 6,087,196, which areincorporated by reference in their entireties, organic vapor phasedeposition (OVPD), such as described in U.S. Pat. No. 6,337,102 toForrest et al., which is incorporated by reference in its entirety, anddeposition by organic vapor jet printing (OVJP), such as described inU.S. patent application Ser. No. 10/233,470, which is incorporated byreference in its entirety. Other suitable deposition methods includespin coating and other solution based processes. Solution basedprocesses are preferably carried out in nitrogen or an inert atmosphere.For the other layers, preferred methods include thermal evaporation.Preferred patterning methods include deposition through a mask, coldwelding such as described in U.S. Pat. Nos. 6,294,398 and 6,468,819,which are incorporated by reference in their entireties, and patterningassociated with some of the deposition methods such as ink-jet and OVJD.Other methods may also be used. The materials to be deposited may bemodified to make them compatible with a particular deposition method.For example, substituents such as alkyl and aryl groups, branched orunbranched, and preferably containing at least 3 carbons, may be used insmall molecules to enhance their ability to undergo solution processing.Substituents having 20 carbons or more may be used, and 3-20 carbons isa preferred range. Materials with asymmetric structures may have bettersolution processability than those having symmetric structures, becauseasymmetric materials may have a lower tendency to recrystallize.Dendrimer substituents may be used to enhance the ability of smallmolecules to undergo solution processing.

Devices fabricated in accordance with embodiments hereof may furtheroptionally comprise a barrier layer. One purpose of the barrier layer isto protect the electrodes and organic layers from damaging exposure toharmful species in the environment including moisture, vapor and/orgases, etc. The barrier layer may be deposited over, under or next to asubstrate, an electrode, or over any other parts of a device includingan edge. The barrier layer may comprise a single layer, or multiplelayers. The barrier layer may be formed by various known chemical vapordeposition techniques and may include compositions having a single phaseas well as compositions having multiple phases. Any suitable material orcombination of materials may be used for the barrier layer. The barrierlayer may incorporate an inorganic or an organic compound or both. Thepreferred barrier layer comprises a mixture of a polymeric material anda non-polymeric material as described in U.S. Pat. No. 7,968,146, PCTPat. Application Nos. PCT/US2007/023098 and PCT/US2009/042829, which areincorporated herein by reference in their entireties. To be considered a“mixture”, the aforesaid polymeric and non-polymeric materialscomprising the barrier layer should be deposited under the same reactionconditions and/or at the same time. The weight ratio of polymeric tonon-polymeric material may be in the range of 95:5 to 5:95. Thepolymeric material and the non-polymeric material may be created fromthe same precursor material. In one example, the mixture of a polymericmaterial and a non-polymeric material consists essentially of polymericsilicon and inorganic silicon.

Devices fabricated in accordance with embodiments hereof may beincorporated into a wide variety of consumer products, including flatpanel displays, computer monitors, medical monitors, televisions,billboards, lights for interior or exterior illumination and/orsignaling, heads up displays, fully transparent displays, flexibledisplays, laser printers, telephones, cell phones, personal digitalassistants (PDAs), laptop computers, digital cameras, camcorders,viewfinders, micro-displays, vehicles, a large area wall, theater orstadium screen, or a sign. Various control mechanisms may be used tocontrol devices fabricated in accordance with the methods hereof,including passive matrix and active matrix. Many of the devices areintended for use in a temperature range comfortable to humans, such as18 degrees C. to 30 degrees C., and more preferably at room temperature(20-25 degrees C.).

The materials and structures described herein may have applications indevices other than OLEDs. For example, other optoelectronic devices suchas organic solar cells and organic photodetectors may employ thematerials and structures. More generally, organic devices, such asorganic transistors, may employ the materials and structures.

The terms halo, halogen, alkyl, cycloalkyl, alkenyl, alkynyl, arylkyl,heterocyclic group, aryl, aromatic group, and heteroaryl are known tothe art, and are defined in U.S. Pat. No. 7,279,704 at cols. 31-32,which are incorporated herein by reference.

It will be readily understood that the components of the embodiments, asgenerally described and illustrated in the figures herein, may bearranged and designed in a wide variety of different configurations inaddition to the described example embodiments. Thus, the following moredetailed description of the example embodiments, as represented in thefigures, is not intended to limit the scope of the embodiments, asclaimed, but is merely representative of example embodiments.

Reference throughout this specification to “one embodiment” or “anembodiment” (or the like) means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment. Thus, the appearance of the phrases “in oneembodiment” or “in an embodiment” or the like in various placesthroughout this specification are not necessarily all referring to thesame embodiment.

Furthermore, the described features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments. In thefollowing description, numerous specific details are provided to give athorough understanding of embodiments. One skilled in the relevant artwill recognize, however, that the various embodiments can be practicedwithout one or more of the specific details, or with other methods,components, materials, et cetera. In other instances, well knownstructures, materials, or operations are not shown or described indetail to avoid obfuscation.

As used herein and in the appended claims, the singular forms “a,” “an”,and “the” include plural references unless the context clearly dictatesotherwise. Thus, for example, reference to “a particle” includes aplurality of such particles and equivalents thereof known to thoseskilled in the art, and so forth, and reference to “the particle” is areference to one or more such particles and equivalents thereof known tothose skilled in the art, and so forth.

As described above, protrusions may be defined as entities having ashadowed region and include, for example, particles defects, deviceelements etc. Large protrusions may, for example, create a surfaceconformation that is difficult to cover/encapsulate in a thin filmdeposition technique. In general, protrusions have dimensions on theorder of micrometers. Typically, there are only a limited number oflarge particles or particle defects on a surface. For example, typicallythere is a distribution of particles sizes on a surface and the largestparticles have the least population. Devices, systems and methods hereofaddress the challenge of covering protrusions, including particles,using thin film deposition techniques with reduction of or eliminationof the need to increase film thickness. In a number of embodiments inwhich a plurality of the protrusions are locally treated, such treatmentresults in treatment of less than 10%, or even less than 1%, of an areaof the surface. That is, the total projected area (on the surface) ofthe treated protrusions is less than 10%, or even less than 1%, of thetotal area of the surface.

In a number of embodiments of methods hereof, known or standard thinfilm deposition techniques are used (for example, in encapsulation ofmicroelectronic devices) to deposit a thin film on relatively smallsurface protrusions without other treatment of such relatively smallprotrusions. However, in such embodiments, larger protrusions aretreated locally and/or selectively to reduce or eliminate the negativeeffect of such protrusions upon a thin film deposition technique (forexample, directional thin film deposition techniques). In that regard,before deposition of a thin film to cover such larger particles, thelarge protrusions may be locally treated to provide a surfaceconformation which can be covered/encapsulated in a thin film depositiontechnique with a decreased film thickness as compared to the filmthickness that would be required to encapsulate the surface withoutlocal treatment of the protrusions.

FIG. 5 illustrates a general methodology for a number of embodiments ofmethods hereof. In a number of representative embodiments of suchmethods described herein, protrusions arising from particle defects on amicroelectronic device are locally treated. However, methods hereof areapplicable generally to substrates for microelectronic devices and toany surface (whether regular or irregular) to which a thin film is to beapplied.

In a number of embodiments hereof, a threshold value for at least onemeasurable aspect (for example, one or more dimensions or a valuedependent thereon) of particles is defined to determine if localtreatment of any of the particles is to be effected. Particles for whichthe measurable aspect exceeds the threshold value are then locallytreated. In general, the local treatment reduces or eliminates theshadowed region associated with a particle or other protrusion. As usedherein, the terms “local”, “locally” and related terms when referring totreatment of a protrusion refer to treatment (for example, to reduce anassociated shadow region) in the vicinity of the protrusion. In general,the surface outside the vicinity of the protrusion is not affected bythe local treatment

FIG. 6 illustrates various actions taken or procedures carried out inconnection with a device 300 and the effects of such actions on device300 and particles thereon in an embodiment of a method hereof. In theillustrated embodiment, a relatively large particle 310 and two smallerparticles 310 a and 310 b on a surface 304 of device 300 areillustrated. Such particles may, for example, be particle defectsintroduced in a manufacturing process of device 300. Particle 310 has anassociated shadowed region 312.

In a number of embodiments, a thin barrier layer 320 may first bedeposited on surface 304 (using a thin film deposition technique) toprotect any underlying layers that may be sensitive to procedures of themethods hereof as, for example, illustrated in procedure (a) of FIG. 6.A conformal coverage is preferred to ensure good coverage everywherearound the one or more particles or other protrusions on surface 304.Depositing initial barrier layer 320 is not required ifprocesses/procedures of the methods hereof will not cause substantialharm to or substantially negatively affect any feature of device 300.

In a number of embodiments, particles requiring treatment under a methodhereof are located via, for example, a scanning process. During thescanning process, particles may be mapped for the entirety of surface304. For example, a laser scanning process may be performed using ascanner 400 as illustrated in procedure (b) of FIG. 6. A surface scanner400 suitable for use herein is the YPI-500 particle scanner availablefrom YGK Corporation of Yamanashi, Japan. For example, a light source(such as a laser) and an image capture device may be used to generateand capture an image of device 300. The image is analyzed via a computerand software executed thereby to, for example, output the size andlocation of particles on device 300. A dimension such as width of theparticles and locations of the particles may be determined. Otherinformation may also be collected. For example, such information mayinclude height, depth, and/or composition of the particles. To excludenormal topological features on surface 304, a reference device (with nodefects) may be used as a control. Alternatively, after scanningmultiple devices, identified repeatable features may be used as areference or control.

In a number of embodiments, a threshold size (which may, for example, bedetermined by a single dimension such a width) for protrusions/particlesthat require treatment is determined, for example, based on the typicaldistribution of particle size and overall consideration of TACT (totalactual cycle time). For example, a particular process may take 5 minutesTACT and can cover protrusions/particles having a width under 3 μm well(that is, in accordance with identified specifications). In thisexample, the treatment of particles may be limited to those having awidth of 3 μm or larger.

Procedures (c) and (d) of FIG. 6 illustrate a representative example ofa localized treatment of particle 310 (which exceeds the threshold valueof 3 μm in width in the above example). In the representative example, aprecursor 500, in a flowable (for example, liquid) form, is applied to(for example, dropped on top of) particle 310. The location of particle310 and the amount or volume of precursor 500 are determined inprocedure (b). Particles 310 may, for example, be modeled as spheres todetermine a volume of precursor 500 to be applied based, at least inpart, on the volume of shadowed region 312 as determined from, forexample, the width of the particle. The more information (for example,width, depth, height, etc.) known about an actual particle, however, themore accurately the volume of precursor 500 can be determined.

Precursor 500 may, for example, be applied by drop coating orinkjet/material printing via a device 600 (for example, aninkjet/material print head). Examples of deposition equipment suitablefor drop-on-demand ink jetting printing include the DIMATIX® printsystems and materials printers available from Fujifilm USA. A volume 504of liquid precursor 500 is accumulated under a perimeter of particle 310to at least partially fill or encompass shadowed region 312. In a numberof embodiments, precursor 500 includes substantially no moisture,solvents or other components to cause significant (or any) damage todevice 300. If the composition of the protrusions is determined, it maydesirable to use different precursors 500 on different protrusions basedon the composition, and thus properties the individual protrusions (forexample, hydrophobicity, hydrophobicity, etc.).

To ensure precursor volume 504 will remain in and/or in the vicinity ofshadowed region 312, some surface treatment may be desirable. In thatregard, actions may be taken so that the surface of particle(s) 310adjacent shadowed region 312 (or under/below the outer perimeter ofparticle 310) is caused to have an affinity for precursor 500 greaterthan the affinity of the remainder of the surface of particle(s) 510 forprecursor 500 and greater than an affinity of surface 304 (or thesurface of film 320, if present) for precursor 500. For example, in thecase of a non-polar liquid precursor 500 (which exhibits an affinity fora hydrophobic surface for adhesion thereto) and a hydrophobic particle310, a directional plasma treatment may be used to make all exposedsurface areas (including, the exposed surfaces of surface 304/film 320and the upper or top (that is, above the outer perimeter of particle310) surface hydrophilic. After the above treatment, the surface ofparticle 310 in or adjacent shadowed region 312 remains hydrophobic. Therelatively greater affinity of the surface of particle 310 adjacentshadowed region 312 for liquid precursor 500, assists in maintainingvolume 504 of liquid precursor 500 in contact with the surface ofparticle 310 adjacent shadowed region 312.

In the case that liquid precursor 500 is non-polar and particle 310 ishydrophilic, an isotropic hydrophobic surface treatment can be used tomake all the surfaces (including the surface of particle 310 in shadowedregion 310) hydrophobic. The isotropic hydrophobic surface treatment maybe followed by an anisotropic (directional) hydrophilic treatment,causing all surfaces other than the surface of particle 310 adjacentshadowed region 312 to be hydrophilic. The surface of particle 310adjacent shadowed region 312 remains hydrophobic. The above procedureswill ensure hydrophobic liquid precursor 500 properly wets and remainsin the vicinity of shadowed region 312. Once again, the volume of liquidprecursor 500 applied may be controlled, based, at least in part, on thesize of particle 310 and the volume of shadowed region 312, to, forexample, predictably reduce the volume of or fill/eliminate shadowedregion 312.

As, for example, illustrated in procedure (d) of FIG. 6, in a number ofembodiments, liquid precursor 500 may be cured or solidified into asolid volume 505 via a polymerization reaction upon application of, forexample, UV energy represented by arrows 710 from a UV source 700. Otherprocesses such as application of oxygen, heat, or moisture may be usedto initiate polymerization. In a number of embodiments, liquid precursor500 includes polymerizable or crosslinkable monomers, oligomers and/orprepolymers. After procedure (d), all shadowed regions 312 under largeparticles 310 (that is, particles 310 satisfying the threshold describedabove) will be eliminated or significantly reduced to, for example,enable all surface areas to be directly exposed to downward depositionof a thin film (for example, a barrier film). Another benefit ofsolidification of precursor liquid 500 is that loose particles 310 willbe held in place by the solidified/polymeric materials 504 a,substantially reducing or preventing the likelihood that such particleswill cause damage to the deposited thin film at a later time (forexample, under stresses of flexing).

As a result of procedure (d), a final thin film 800 may be deposited inprocedure (e) of FIG. 6. Thin film 800 may provide good coverage of allprotrusions/particles 310 as illustrated in FIG. 6. By locally orselectively treating relatively large particles 310, the thickness offilm or layer 800 (or the combined thickness of film 320 and film 800)may be significantly less than thin films applied via currently usedthin film deposition techniques when large particle defects are present.Locally or selectively treating relatively large protrusions effectivelyeliminates or substantially reduces the severity of overhangs orextending perimeters/edges which, for example, create shadowed regions,thereby facilitating surface coverage with significantly thinner filmsthan possible under currently used thin film techniques in the presenceof relatively large protrusions. The material of thin film 800 may bethe same as or different from the material used for barrier layer orfilm 320. Moreover, as described above, when the procedures used tolocally or selectively treat large protrusions hereof do not causesubstantial damage to device 300, thin barrier film 320 need not bedeposited.

In a number of embodiments, more detailed information may, for example,be detected during the procedure for scanning a surface to, for example,identify and locate protrusions. If particles can be determined to be onthe top of device 300 (or another surface), one or more particle(s) 310may be removed via, for example, a small vacuum pick-up device or vacuumtip 900 (see FIG. 7A) brought into contact with particle 310. Particles(for example, particles satisfying a particular measurable threshold(which may be the same as or different from the dimensional thresholddiscussed above) may be removed or decreased in size via othertechniques, including but not limited to, selectively etching (eitherfully or partially). Similar to applying a material to a particle asdescribed above, locally or selectively treating particles by removalthereof or reducing the size thereof results in reduction or eliminationof shadowed regions associated with the treated particles and obviatesthe need to grow thicker thin films. Removal and/or reduction in size ofparticles may, in certain embodiments, eliminate the need to apply amaterial to particles to reduce or eliminate shadowed regions asdescribed above in connection with FIG. 6. Further, removal and/orreduction in size of particles may, in other embodiments, be used inconnection with application of a material to particles to, for example,reduce or eliminate shadowed regions. For example, removal and/orreduction in size of particles may occur before or after procedures (a)or (b) described above in connection with FIG. 6.

Etching may, for example, be done by a localized laser beam 1000 as, forexample, illustrated in FIG. 7B. As illustrated in FIG. 7C, if a laserbeam 1000 a can be set, for example, horizontal or otherwise generallyparallel to a surface (for example, of surface 304 of a device 300) andcan be suitably controlled, a scan to identify, for example, largeparticles may not be required. Such a horizontal etching may, forexample, be performed at any time even before the growth of the firstbarrier film (taking care that a device or other surface does not becomedamaged) to etch the particles down to a specific size. Plasma etchingmay also be used. If a particle to be decreased in size or removed viaetching is formed from a polymeric material, the particle can be etchedby selecting an etching plasma which etches only polymers but not thematerial of, for example, barrier film 320 or surface 304 (if barrierfilm 320 is absent).

In a representative example of a method hereof, particle size is used inthe decision making process. Size in this example refers to the largestdimension in a two-dimensional projection of the particle on the surfaceof, for example, a microelectronic device such as or including anintegrated circuit, a charge coupled device, a light emitting diode, alight emitting polymer device, an organic light emitting device, a metalsensor pad, a micro-disk laser, an electrochromic device, a photochromicdevice, a display, an organic electronic device, amicroelectromechanical system, a thin film transistor or a solar cell.Such microelectronic devices typically include multiple layers disposedupon a substrate. The surface may also be the surface of the substratefor a microelectronic device upon which such layers are later deposited.In a number of embodiments, the surface is a surface of an organic lightemitting diode or a substrate therefor.

In a number of embodiments, the threshold dimension of protrusion sizethat is to be identified for local treatment is determined, at least inpart, on the basis of TACT. For example, if the thin film encapsulationprocess being used can encapsulate particles up to 2 μm while meetingTACT requirements, the lower limit/threshold for particles that requiretreatment is set at 2 μm. After determination of the particle dimensionthreshold, a scan is performed to determine the dimension and locationof all the particles that have a dimension larger than 2 μm using, forexample, a YPI-500 surface particle scanner. Optionally, if one or moreparticles are detected to be on the very top layer of the device, avacuum pick-up device or tip may be used to remove such particles.

As describe above, a thin film layer or barrier layer may be applied toprotect the underlying device from potential damage. Many thin filmencapsulation processes may be used in this procedure. An example, ofsuch a thin film encapsulation method is described in U.S. Pat. No.7,968,146. The barrier layer may be very thin, and is optional if thesubsequent procedures will not cause substantial or excessive damage tothe device. Examples of suitable materials for the barrier layerinclude, but are not limited to, inorganic materials, organic materials,and/or metallic materials.

After optional deposition of a barrier layer, local treatment ofparticles/protrusions may be performed via an ink-jet printing headbrought into operative connection with each particles identified to havea dimension greater than the 2 μm threshold. Based on the particle size,a sufficient volume of a liquid precursor, which may include onlymonomers, oligomers, and/or prepolymers is, for example, dropped on theparticles to suitably reduce the size of or fill the shadowed regionsassociated with the identified particles. Examples of suitable liquidprecursor materials include acrylate or epoxy monomers, oligomers orprepolymers. The liquid precursor may, for example, be applied using inkjetprinting equipment as described above. The liquid precursor is, forexample, polymerized using a UV light source or a thermal source to cureor crosslink the monomers, oligomers and/or prepolymers thereof. Theresultant cured volume of material may, but need not, have an averageperimeter which increases in a downward direction as illustrated, forexample, in FIG. 6. Optimization of the volume of the liquid precursoror other shadow region filling material may be used to ensure adequatecoverage using a particular thin film deposition technique. In a numberof embodiments, it may be desirable to minimize the footprint thematerial reducing the size of the shadowed region and/or to minimize thetime required to complete the subsequent thin film deposition process.Optimization criteria may differ for different applications, fillingmaterials etc.

After curing of the liquid precursor, the thin film encapsulationprocess is then completed at the specified TACT. The thin firmdeposition or encapsulation process described in U.S. Pat. No. 7,968,146may, for example, be used. Likewise, the thin film deposition processdescribed in U.S. Pat. No. 6,548,912 may be used. A plurality of thinlayers of different composition may, for example, be applied ordeposited to form a thin film. For example, multiple layers of alternateinorganic/organic films, alternate inorganic films of different type,alternate hybrid films, or alternate inorganic/organic/metallic filmsmay deposited. The thin film deposition process of U.S. PatentApplication Publication No. 2008/0102223 may also be sued. In a numberof embodiments, the encapsulating film thickness applied in the thinfilm deposition may, for example, be in the range or approximately 0.1μm to 5 μm (not including the thickness of any barrier film 320, whichmay, for example, have a thickness in the range of approximately 0.01 μmto 1 μm).

Thin film deposition techniques are often, for example, used to depositfilms having a thickness on the scale of nanometers to micrometers. Adesirable film thickness may, for example, be in the range ofapproximately 0.1 μm to 5 μm. Typically the required total thickness forthe thin film encapsulation is the thickness needed for encapsulating aperfect defect free surface plus the thickness needed to coverprotrusions/particles. The film thickness typically required to coverprotrusions is typically half of the height (size) of the largestprotrusions. For example, in the case of a surface having protrusionswith the size of 10 μm and a thin film capable of encapsulating a defectfree surface with 1 μm thickness, the total thin film thickness requiredis 6 μm (10/2+1). With the local treatment of protrusion larger than 2μm as described herein, the total thickness of the required film will bereduced to 2 μm (2/2+1), which is a 67% reduction of thin filmthickness, and thus TACT.

In a number of embodiments hereof, protrusions may be locally treatedwithout the need to identify protrusions satisfying a threshold value.FIG. 8 illustrates various actions taken or procedures carried out inconnection with device 300 (as described above) and the effects of suchactions on device 300 and protrusions/particles 310, 310 a and 310 bthereon in such an embodiment of a method hereof. As described above, athin barrier layer 320 may optionally first be deposited on surface 304to protect any underlying layers that may be sensitive to procedures ofthe methods hereof as, for example, illustrated in procedure (a) of FIG.8. As described above, the surfaces bordering the shadowed region of allprotrusion may be caused to have a unique, selective affinity for aflowable precursor. Procedures/devices 450 used in effecting suchselective affinity are represented schematically in procedure (a) ofFIG. 8. Once such selective affinity is achieved, flowable (for example,liquid) precursor 500 may be applied to the entire surface asillustrated in procedure (b) of FIG. 8. A sufficient volume of precursor500 may, for example, be applied to ensure that precursor 500 fills theshadowed regions of all protrusions.

The bulk of precursor 500 may then be removed (for example, via a dryingprocess, gravitational drainage etc.) as illustrated in procedure (c) ofFIG. 8. Because of the affinity of surfaces of bordering the shadowedregions of all protrusion, a volume 504, 504 a and 504 b of precursor500 will remain in the vicinity of the shadowed regions of eachprotrusion 310, 310 a and 310 b (in the illustrated example). Liquidprecursor 500 may, for example, be applied in a spraying or sputteringprocess.

As, for example, illustrated in procedure (d) of FIG. 8, in a number ofembodiments, liquid precursor 500 may be cured or solidified into asolid volumes 505, 505 a and 505 b via a polymerization reaction uponapplication of, for example, UV energy represented by arrows 710 from aUV source 700. Once again, other processes such as application ofoxygen, heat, or moisture may be used to initiate polymerization. As aresult of procedure (d), a final thin film 800 may be deposited inprocedure (e) of FIG. 8.

This disclosure has been presented for purposes of illustration anddescription but is not intended to be exhaustive or limiting. Manymodifications and variations will be apparent to those of ordinary skillin the art. The example embodiments were chosen and described in orderto explain principles and practical application, and to enable others ofordinary skill in the art to understand the disclosure for variousembodiments with various modifications as are suited to the particularuse contemplated.

Thus, although illustrative example embodiments have been describedherein with reference to the accompanying figures, it is to beunderstood that this description is not limiting and that various otherchanges and modifications may be affected therein by one skilled in theart without departing from the scope or spirit of the disclosure.

1-36. (canceled)
 37. A method of encapsulating a device including aplurality of protrusions extending therefrom, comprising: locallytreating at least one of the protrusions; and depositing a thin film toencapsulate the device after local treatment of the at least oneprotrusion.
 38. The method of claim 37 further comprising defining athreshold value for at least one measurable aspect of the protrusions todetermine protrusions for which local treatment is to be effected. 39.The method claim 37 further comprising depositing a protective, thinbarrier layer on the device prior to locally treating the at least oneprotrusion.
 40. The method claim 37 wherein the thin film comprises atleast one of an inorganic material, a metallic film, or an organicmaterial.
 41. The method of claim 40 wherein the thin film comprises atleast one of an inorganic material, an organic material, or a metallicmaterial.
 42. The method of claim 41 wherein the inorganic material isan oxide, a nitride, or an oxynitride.
 43. The method of claim 41wherein the organic material is an acrylate or a siloxane.
 44. Themethod claim 37 wherein the thin film comprises a plurality of layers.45. The method claim 44 wherein thin film comprises a layer of a firstmaterial and at least a second layer of a second material different fromthe first material.
 46. An encapsulated device, comprising: a surfacecomprising a plurality of protrusions extending therefrom, and a thinfilm deposited to encapsulate the device, wherein at least one of theplurality of protrusions has undergone local treatment prior todeposition of the thin film.
 47. The device of claim 46 whereinprotrusions exceeding a threshold value for at least one measurableaspect of the protrusions have undergone local treatment to reduce thethickness of the thin film required to encapsulate the device.
 48. Amicroelectronic device, comprising: a surface comprising a plurality ofprotrusions extending therefrom, and a thin film deposited toencapsulate the microelectronic device, wherein at least one of theplurality of protrusions has undergone local treatment prior todeposition of the thin film.
 49. The microelectronic device of claim 48wherein protrusions exceeding a threshold value for at least onemeasurable aspect of the protrusions have undergone local treatment toreduce the thickness of the thin film required to encapsulate themicroelectronic device.
 50. A system for preparing a surface fordeposition of a thin film thereon, wherein the surface includes aplurality of protrusions extending therefrom which have shadowedregions, comprising: at least one detecting device to locate protrusionsatisfying a threshold value for at least one measurable aspect of theprotrusions; and at least one device to locally treat at least one ofthe protrusions for which the measurable aspect exceeds the thresholdvalue.